This invention generally relates to safety lockout switches, and more particularly, to an ambidextrous switch lockout system.
Some power saws, such as miter saws, have safety lockout buttons that require actuation before a power switch can be turned to the on position. Safety lockout buttons effectively minimize the probability of accidental tool activation by requiring the user to follow a sequence of at least two steps before activation.
Conventional lockout buttons are spring-loaded and include an internal blocking feature that mechanically interferes with the travel of a power switch trigger or lever. After the power switch is released to an off position, the system resets, and again requires at least two steps before the tool can be activated again.
Some conventional safety lockout systems include a removable button with a hole for receiving the button. When the removable button is not in place in the hole, the tool cannot be powered up. The removable button is intended to decrease the probability for accidental tool activation by adding an additional step to the process used for activating the tool. However, the removable button is an inconvenience if lost. A lost removable button can be more than an inconvenience, and may present a safety problem, for example, if users force other items into the hole to replace the lost removable button.
Power saws with vertical handles may also have a lockout button protruding from a left side of the handle, near the switch trigger. This conventional system is not ambidextrous. When used with a right hand, the lockout button is actuated by a thumb and the switch trigger by an index finger. When used with a left hand, the lockout button and switch trigger are usually both actuated by an index finger of the left hand.
The invention disclosed by U.S. Pat. No. 5,969,312 to Svetlik et al. (xe2x80x9cthe ""312 patentxe2x80x9d) is for an ambidextrous lockout switch. Although the lockout switch of the ""312 patent can be operated by both a left handed user and a right handed user, and is in this sense xe2x80x9cambidextrousxe2x80x9d, the method for using the ambidextrous lockout switch of the ""312 patent is substantially different for a right handed user than for a left handed user, and is not truly ambidextrous in this sense. In particular, a left handed user must rely on a xe2x80x9cslide switch 22xe2x80x9d, whereas a right handed user activates a xe2x80x9cpressure button 23xe2x80x9d for actuation.
There is, therefore, a need in the art for a switch lockout system that is convenient for use by both left and right handed users, and is actuatable in a substantially similar way by both left and right handed users.
The present invention provides a generally balanced ambidextrous switch lockout system, actuatable in the same way by both left handed and right handed users. On a horizontally oriented handle, left handed and right handed users perform substantially the same steps to activate the power. The left side lockout button is identical to the right side lockout button in appearance and function. In the system of the present invention, both the left handed and right handed users press the right and left lockout buttons, respectively, with a thumb. The system of the present invention resets automatically after a switch lever or trigger is released. The system of the present invention may be added to a multi-position handle, which can be selectively oriented in a plurality of positions, including both horizontal and vertical positions. The present invention is ambidextrous, i.e., suitable for use by both left handed and right handed users, in any of the plurality of positions.
In a first embodiment, the present invention generally includes: a left lockout button, a right lockout button, a linkage, a centering spring, and a switch lever. The left lockout button is pivotally mounted to the left side of a horizontal handle with a protrusion from the left side of the handle. The protrusion on the left side of the handle is intended for thumb actuation by the right hand of a user when the handle is in a generally horizontal position. On a rotatable handle, when the handle is in a generally vertical position, the left lockout button is on top, and the one left lockout button may be activated by either a left handed user or a right handed user in substantially the same way. The left lockout button includes a barrier intended to stop actuation of the switch lever. The left lockout button has an aperture spaced apart from where the left lockout button is pivotally mounted. The aperture allows for a hinged connection to the linkage between the left lockout button and the right lockout button. The left lockout button also has two fingers that contact opposite ends of a centering spring.
The right lockout button is substantially a mirror image of the left lockout button, but without the barrier or the two fingers for contacting a centering spring. The thumb of the left hand of a user presses a protrusion from the right side of the handle. The right lockout button also has an aperture for mechanical coupling (through the linkage) between the left lockout button and the right lockout button. With both left and right lockout buttons mounted to the handle and the linkage connecting them, pressing the left lockout button causes the protrusion of the right lockout button to move leftwardly, and pressing the right lockout button causes the protrusion of the left lockout button to move rightwardly.
The centering spring is mounted to the handle in a spring mount, which holds a first and a second end of the spring. The spring mount is under the left lockout button, and has left and right ends, with interruptions in both left and right ends to allow the two fingers of the left lockout button to penetrate as the left lockout button moves. Pressing on the left lockout button causes the right finger to compress the centering spring to the left. Because of the linkage, pressing down on the right lockout button causes the left finger to compress the centering spring to the right. When neither the left lockout button nor the right lockout button has been pressed, both are held by the centering spring at a blocking position. At the blocking position, the barrier of the left lockout button blocks movement of the switch lever, preventing actuation of the switch lever. When the left lockout button is pressed, the barrier moves leftwardly, outside the switch lever, and allows the switch lever to be actuated. When the operably linked right lockout button is pressed, the barrier of the left lockout button moves rightwardly, inside the switch lever, and allows the switch lever to be actuated by an inward movement.
In a first embodiment, the present invention includes an ambidextrous lockout switch including a handle body with a first side and a second side, a switch, a barrier, a first lockout button, a second lockout button, and a spring. The switch is mounted to the handle body, and extends outwardly from the handle body. The switch can be actuated by an activating movement, which might be an inward, squeezing movement The barrier is mounted inside the handle body, and is movable from a blocking position in which the activating movement of the switch is blocked. The first lockout button is movably mounted to the handle body, and is adapted for moving the barrier in and out of the blocking position. Operably linked to the first lockout button is the second lockout button, with the second lockout button also adapted for moving the barrier in and out of the blocking position. The spring, which is mounted inside the handle body, is mechanically coupled to the barrier, and biases the barrier toward the blocking position when the barrier has been moved away from the blocking position by either the left lockout button or the right lockout button.
Optionally, the barrier and the switch may have complementary surfaces, which are shaped to maximize surface contact between the barrier and the switch when the barrier is in the blocking position. The switch may have a generally conical surface, with the barrier having a generally inverted conical surface. The barrier will generally return back into the blocking position after a small movement away from the blocking position because of the complementary surfaces.
In another embodiment, the first lockout button is pivotably movable around a pivot mount near the first side of the handle body. In some embodiments, the barrier may be fixed to the first lockout button so that a pivotal movement of the first lockout button results in a movement of the barrier away from the blocking position.
In other embodiments, the second lockout button may also be pivotably movable around a pivot mount near the second side of the handle body. In such embodiments, the barrier may also be movable away from the blocking position by pivoting of the second lockout button, since the second lockout button and the first lockout button are operably linked. Optionally, the operable link between the first lockout button and the second lockout button may be a linkage.
Optionally, in some embodiments, the first lockout button may have at least one finger extending outwardly, adapted for contacting the spring. When the barrier (mechanically coupled to the first lockout button) is moved away from the blocking position, the finger of the first lockout button is effective for compressing the spring.
As will be recognized by those of skill in the art, in many embodiments, it is convenient to refer to xe2x80x9cthe first side and the second sidexe2x80x9d as xe2x80x9cthe left side and the right sidexe2x80x9d, although it is not necessary to the present invention that the first side and the second side be assigned to a particular direction or handedness. For example, the first side might also be called the xe2x80x9cright sidexe2x80x9d and the second side might be called the xe2x80x9cleft side.xe2x80x9d The first side could be called xe2x80x9cthe top sidexe2x80x9d and the second side might be called xe2x80x9cthe bottom side.xe2x80x9d All that is required for the present invention is a handle body with both a first side and a second side.
In another embodiment, the present invention is also directed to an ambidextrous switch lockout system. The system is for use with a handle body with a first side and a second side, and the system includes a switch, a first lockout button having a protrusion and a barrier, a second lockout button having a protrusion, and a spring. The switch is mounted to the handle body, extends outwardly from the handle body, and is actuatable by an activating movement, which might be an inward, squeezing movement when the switch is a switch trigger or lever.
In such an ambidextrous switch lockout system, the first and second lockout buttons are pivotably mounted to the handle body. The protrusion of the first lockout button protrudes from the first side of the handle body, and the protrusion of the second lockout button protrudes from the second side of the handle body. The barrier of the first lockout button is adapted to prevent the activating movement of the switch (and hence, the actuation of the switch), by physically blocking the activating movement when the barrier is in a blocking position. The barrier is, however, movable from the blocking position by pressing of both the first lockout button and the second lockout button. When pressed, the first lockout button pivots the barrier away from the blocking position in a first direction, and the second lockout button pivots the barrier away from the blocking position in a second direction. The second lockout button and the first lockout button may also be operably linked, so that the movement of the second lockout button results in movement of the barrier, which, in an embodiment, is part of the first lockout button. As will be recognized by those of skill in the art, in other embodiments, the barrier may be part of the second lockout button. In any embodiment, the spring mounted to the handle body is mechanically coupled to the barrier, so that the barrier is biased toward the blocking position.
As described in connection with another embodiment of the present invention, the barrier and the switch may optionally have complementary surfaces shaped to maximize surface contact between the barrier and the switch when the barrier is in the blocking position.
The first lockout button may, in some embodiments, also include at least one finger extending outwardly for contacting the spring. When the first lockout button is moved, the finger compresses the spring. Since the barrier is connected with the first lockout button, the spring is capable of moving the barrier toward the blocking position.
In another embodiment, the blocking position is associated with a defined starting angle for the first lockout button. Pressing the protrusion from the first lockout button pivots the first lockout button away from the starting angle in either a first direction or a second direction. When the first lockout button is within a first angle in the first direction or a second angle in the second direction, the activating movement of the switch is prevented. However, when the first lockout button is moved beyond the first angle in the first direction away from the starting angle or the second angle in the second direction away from the starting angle, the activating movement of the switch becomes possible. In such an embodiment, the spring is effective for restoring the first lockout button to the starting angle, where the spring is in a minimally compressed state.
As will be recognized by those of ordinary skill in the art, it is not necessary to the present invention that the first lockout button or the second lockout button be pivotally mounted to the handle body. In other embodiments of the present invention, the first lockout button or the second lockout button may be slidably mounted to the handle body. In such embodiments, the blocking position of the barrier may not be defined by a starting angle, since the barrier need not move pivotally in every embodiment. In another embodiment, the blocking position may be defined with reference to another portion of the device. All that is necessary to the invention is that the barrier block the activating movement of the switch
In yet another embodiment, the present invention provides an ambidextrous lockout switch system for use in a handle body including a switch, a means for blocking, at least two means for selectively moving the means for blocking, and a means for biasing. The switch is generally actuatable by an activating movement. The means for blocking is used to block the activating movement when the means for blocking is in a blocking position. The means for biasing provides a force for restoring the means for blocking to the blocking position.
In some embodiments, the at least two means for selectively moving are a first lockout button and a second lockout button, the first lockout button and the second lockout button being operably linked. Optionally, the second lockout button may be operably linked to the first lockout button by a linkage. Also optional (as explained above) is an embodiment in which the first lockout button is pivotably mounted to a first side of the handle body and the second lockout button is pivotably mounted to a second side of the handle body. The means for blocking may be fixed to either the first or the second lockout button, so that the means for blocking is movable away from the blocking position with either the first lockout button or the second lockout button. In some optional embodiments, at least one finger may extend outwardly toward the means for biasing from one of the at least two means for selectively moving. In such an embodiment, the at least one finger is adapted for contacting the means for biasing. Finally, the means for biasing may be a spring mounted inside the handle body and mechanically coupled to the at least two means for selectively moving. Other means for biasing, such as an plastic flap or rubber band are possible.